Why are there no tutorials of flames in blender render?
Blender Internal is well documented in the Blender Manual including smoke and fire domains. You will find what the settings do and how to set it up to make it work. It doesn't teach you how to put the pieces together to make a good looking fire simulation though.

For that you can try Miika Hamalainen's blog, he is the fire module owner and also wrote the code. This was part of Google Summer of Code 2012, when Blender was at version 2.65.

On the blog site there are some fire examples from times when Cycles didn't even had support for volumetrics. You will find what force-fields and noise textures to set, what values to animate for nice looking fires etc. At that time it was thee resource for fire from even which other tutorial makers got knowledge.

After these years, search engines bury old results and promote the ones people mostly want, which nowadays is for Cycles. So you need to dig deep or search with more specific criteria, like "blender fire 2.6" which yields this video for example and some others.

There is also the old BlenderGuru's flamethrower tutorial.

The user-base back then was way smaller, so that's why there are less tutorials. They got buried by search engines and by many more tutorials for Cycles.